1. A Golden Anniversary for a Golden Computer Brian L. Stuart Drexel University

2. Origins of the PDP-8 Foxboro Corporation and process control CDC 160 by Seymour Cray influenced MIT LINC by Wes Clark influenced DEC DC-12 marketed as PDP-5

3. PDP-5 Introduced in 1963 6 μS Memory cycle time 12-bit word To match analog to digital converters Front end for PDP-4 Up to 32KW of memory Built with DEC System Modules

4. PDP-5

5. Flip Chip Modules Introduced in 1964 Faster than System Modules 2 7/16 in by 5 in Roughly equivalent to later SSI logic ICs

6. Flip Chip Modules

7. From PDP-5 to PDP-8 Re-implement PDP-5 architecture: Move program counter to register Use flip chip modules Same I/O devices Faster 1.6 μS memory

8. The Straight 8

9. PDP-8/S Bit serial implementation Less expensive and slower

10. PDP-8/I Re-implementation using TTL ICs

11. PDP-8/L Low cost packaging of PDP-8/I design

12. PDP-8/E,F,M Reimplementation using larger boards Lower cost OMNIBUS

13. PDP-8/A Larger OMNIBUS boards Keypad front panel

14. PDP-8 Register Architecture Single accumulator Single link bit (carry bit) Program counter MQ register No Stack pointer

15. PDP-8 Memory Architecture 32KW maximum memory 8-4KW fields 32-128 word pages per field Addressing:  Current page direct  Zero page direct  Indirect  Auto-increment indirect

16. PDP-8 Instruction Set 8 Major Instructions  AND: bitwise and  TAD: 2's complement add  ISZ: increment and skip if zero  DCA: deposit and clear accumulator  JMS: jump to subroutine  JMP : jump  IOT: in-out transfer  OPR: operate

17. PDP-8/M Restoration

20. PDP-8 Impact Sub $20K Conventional power Table-top size Multiple languages and peripherals Bus structure → All point to early microcomputer designs